A firewall is a piece of equipment that monitors the incoming and outgoing network traffic for your business. A business class firewall can do things like content filtering, intrusion protection, malware filtering, virus filtering, and more. The largest advantage with a firewall is the ability to control what passes through to your network and what does not. For example, if you have a policy that bans social media browsing while at work, you can do so with your firewall. If you do not want folks shopping for personal items on Amazon while at work, you can prevent them from going to those sites. The ability to have this much control over the traffic running through your network limits liability, as well as keeps employees on task so they are not distracted by checking Facebook or busy shopping on Amazon.